\”BPD-FL>2\” formula is called the password for giving birth to a boy. It calculates the biparietal diameter of the fetus minus the length of the femur. If it is greater than 2, it means the baby is a boy; if it is less than 2, it means the baby is a girl. In addition, BPD data can also predict the expected date of delivery and fetal weight, and normal head circumference data indicates that the fetus is well developed and easy to deliver naturally. The gender of the fetus can be most accurately determined when a B-ultrasound is performed around 8 weeks.
Compared with other methods such as fortune telling and ancestral secret recipes, which have no scientific basis and low accuracy, the \”BPD-FL>2\” formula is based on medical research and a large number of experiments and has a high accuracy. For target users, they are more concerned about the results and prediction accuracy, and less concerned about what technology or equipment is used in the process. 
Is there any scientific basis for the claim that biparietal diameter minus femoral length can determine male and female?
It is completely wrong to say that if the biparietal diameter minus the femoral length exceeds 2 on B-ultrasound, a boy will be born. This is completely wrong and has no scientific basis. Generally speaking, when you are 4 to 5 months pregnant, you can directly determine the gender of the fetus through ultrasound examination.
Generally speaking, when the pregnancy is full term, the biparietal diameter of the fetus should be more than 9.3cm. According to general rules, after 5 months of pregnancy, it is basically the same as the pregnancy month. That is to say, when you are 28 weeks pregnant, that is, 7 months old, the biparietal diameter is about 7.0cm, when you are 32 weeks pregnant, or 8 months pregnant, it is about 8.0cm, and so on. After 8 months of pregnancy, it is normal to gain an average of about 0.2cm per week. This information is often measured when confirming fetal weight.
The numerical difference between the fetal biparietal diameter and the femur is different for each fetus and has nothing to do with male or female. Pregnant mothers, think about it, some fetuses have larger fetal heads. For example, the biparietal diameter shown by B-ultrasound at 30 weeks of pregnancy is the standard value for 31-32 weeks of pregnancy, then the difference between the biparietal diameter and femoral length is likely to be greater than 2, and vice versa. 
During pregnancy, try not to be exposed to electronic radiation products for a long time, such as computers or mobile phones, especially in the early stages of pregnancy, which may affect the fetus. You also need to maintain a stable mood and try to avoid too much mood swings. Listen more Soothing music.
